> To my mind if you say "next week" then that refers to the very next week that comes along after this week. You wouldn't mean the first week in the next month (unless it WAS also the first week in the next month). So if you say "next X-day" the next should refer not to the week but to the very next day of that name that comes along. (?)

We keep this one clear by distinguishing for instance: "coming Saturday " from " next Saturday " ( e.i. next week's Saturday).
"aanstaande zaterdag" versus "volgende zaterdag".